..Our analyses suggest that while there may be mean differences in the levels of depressive symptoms across sexes, the genetic and environmental factors that predispose males and females to depressive symptoms are not different...

..Are there risk factors that associate with illicit drug use or illicit drug abuse/dependence? Is the magnitude of the association the same for use and abuse/dependence? Does this pattern of association differ across categories of drugs?..

..NS was most closely related to cannabis use while N showed significant genetic overlap with sedative use. NS in males appears to be a good indicator of risk for cannabis use. This result may be useful for candidate gene studies...

How phenotype and developmental stage affect the genes we find: GABRA2 and impulsivity

..We conclude that the criteria that serve as indicators of DSM-IV cannabis abuse and dependence do not function identically in men and women and that certain criteria (e.g. hazardous use) require further refinement...

Are there genetic influences on addiction: evidence from family, adoption and twin studies

..With a focus on the classical twin design that utilizes data on monozygotic and dizygotic twins, we discuss support in favor of heritable influences on alcohol, nicotine, cannabis and other illicit drug dependence...

Long-term stability and heritability of telephone interview measures of alcohol consumption and dependence

..42 to .51 for dependence and from .31 to .51 for consumption. Consumption was significantly less heritable in the younger Phase 2 cohort (23-39 years) compared to the older Phase 1 cohort (28-90 years)...

..Despite accumulating evidence that there is a genetic basis for cannabis use disorders (ie, abuse and dependence), few studies have identified genomic regions that may harbor biological risk and protective factors...

Correlates of cigarette smoking during pregnancy and its genetic and environmental overlap with nicotine dependence

..In adolescent girls especially, rates of cannabis use have increased over the last decade, urging the need to characterize the potential correlates of onset of cannabis use during emerging adulthood...

Correlates of regular cigarette smoking in a population-based sample of Australian twins

..We examine the co-occurrence of abuse/dependence across different illicit drugs and test associations between these classes and major psychiatric disorders...

Subtypes of illicit drug users: a latent class analysis of data from an Australian twin sample

Michael T LynskeyDepartment of Psychiatry, Washington University School of Medicine, St Louis, Missouri 63110, United States of AmericaTwin Res Hum Genet 9:523-30. 2006

..Aggregation of population-level data may obscure important subgroup differences in patterns of illicit drug use and psychiatric comorbidity. Further exploration of a 'self-medicating' subgroup is needed...

Assortative mating for cigarette smoking and for alcohol consumption in female Australian twins and their spouses

..We investigated whether use and early-onset use of cigarettes, alcohol and cannabis contributed an increase in risk for initiation of subsequent psychoactive substances in women (N = 3729, mean age = 21.7)...

Association of GABRA2 with drug dependence in the collaborative study of the genetics of alcoholism sample